1. Field of the Invention
This invention relates to energetic compositions such as propellants, decoy compositions, obscurants, illuminants, gun propellants, target markers, tracer munitions, and gas generants. More particularly, the invention is directed to compositions and methods for enhancing the burn rate of such energetic materials.
2. Technology Background
The burn rate of energetic compositions such as propellants, pyrotechnics, and gas generants is defined as the distance traveled per second by the flame front perpendicularly to the exposed surface of the energetic material. The burn rate is dependent upon the pressure of the surrounding gas phase. The relationship may be expressed r=KP.sup.n, where r is the burn rate, K is a proportionality constant, P is the absolute pressure, and n is the pressure exponent.
Often it is desirable to tailor the burn rate to specific applications. Tailoring the burn rate of energetic compositions is important to the design of articles with specific burn times and mass flow outputs. For example, a pyrotechnic obscurant composition with a low burn rate may not produce enough smoke to provide the desired obscuration effect. If a propellant burn rate is too low, then the gas output or thrust may be insufficient. Similarly, if a gas generant's burn rate is low, then the gas output may be insufficient to inflate a supplemental restraint device. Visible light and infrared illuminant flares with a low burn rate may not provide sufficient illumination.
Some additives are known to enhance the burn rate of energetic compositions. For example, iron oxide and catocene are two commonly used burn rate accelerants. They are often used with energetic compositions that contain ammonium perchlorate as the oxidizing agent. However, these burn rate accelerants have disadvantages. For instance, catocene is known to increase the friction and impact sensitivity of the energetic composition. Iron oxide is generally only effective for ammonium perchlorate systems. Its usefulness is limited in other oxidizer systems.
From the foregoing, it will be appreciated that there remains a need in the art for methods for enhancing the burn rate of energetic compositions.
Such methods for enhancing the burn rate of energetic compositions are disclosed and claimed herein.